The present invention relates to an apparatus for reproducing video signals in which the position of a rotary magetnic head is controlled transverse to successive parallel tracks formed obliquely with respect to the longitudinal direction of tape, so that tracking control may be performed in accordance with the reproducing tape speed.
In a video tape recorder (to be referred to as a VTR for brevity hereinafter) wherein video signals of one field are recorded on a single oblique track, framing control is performed during reproduction so as to make the odd and even fields of reproduced video signals and of external reference synchronizing signals repectively coincide with each other. A certain type of VTR has a check function for checking the coincidence between the odd and even fields determined by the synchronizing signals (i.e., vertical, horizontal, bursts and so on) included in the reproduced video signals with those of the external video signals. If they do not coincide, a control signal is supplied to a capstan servo system to shift the reproducing track phase. In another type of VTR, a method is adopted wherein framing control is performed by adding odd/even information of the field to a control signal CTL recorded on the edge of the tape, and operating the capstan servo system by the control signal. This method is adopted in the type C standards of the SMPTE (society of Motion Picture and Television Engineers) for broadcasting 1/inch VTR.
Framing control is performed in general VTRs in the ways described above. However, other problems are encountered in another type of VTR which has a movable head for reproduction at various speeds (a dynamic tracking head). In a VTR of the dynamic tracking type, a rotary magnetic head is mounted on an electromechanical converting element such as a bimorph leaf, and the position of the rotary magnetic head is controlled in the direction perpendicular to the scanning direction thereof (that is, widthwise). In a VTR of this type, while reproduction is being performed, tracking error between the recording tracks formed on magnetic tape and a head tracing path is corrected. For this reason, high-quality images may be reproduced without guard band noise in a variety of speed reproduction modes such as slow, still, fast and reverse.
In a VTR with a dynamic tracking head of this type, simultaneously with correction of the tracking error, head jump (or track jump) is performed after tracing each track for selecting the next scanning track. However, when such a jump (position control) of the head is performed, the odd/even order of the reproduced signal fields may be disturbed in each of the various speed reproduction modes such as slow, still, and fast. For example, a VTR is known which has a tracing control system which makes a head jump to a next track which is closest to the head when the head position control amount (displacement) exceeds a predetermined value at the terminal end of a track. However, an unexpected track change may be made with track deformation of less than 100 .mu.m, which disturbs the odd/even order of the reproduced signal fields.
In order to solve this problem, a system has been proposed whereby the odd/even order may not be disturbed wherein the odd/even information of the reproduced, signal fields is compared with that of an external reference synchronizing system, and the comparison results are added to the conditions for making a head jump. However, such a system requires extra detectors and more often causes erratic operation due to an increased number of jump conditions.
The present invention has been made in consideration of this and has for its object to provide a head position control system which may not cause disturbance in the odd/even order of the reproduced signal fields.